Mixed block polymer adhesive

Abstract

A broad performance pressure-sensitive adhesive based upon A-B-A and A-B block copolymers. The adhesive possesses a superior balance of properties when extruded and comprises a major proportion of styrene-isoprene-styrene A-B-A block copolymer elastomers and a minor proportion of styrene-isoprene A-B block copolymer elastomers, in its elastomeric component. Suitable proportions of tackifier resins for these elastomers also are included.

What is claimed is: 
     
       1. A pressure-sensitive adhesive composition comprising a thermoplastic elastomeric component and a resin component; said thermoplastic elastomeric component consisting essentially of about 50-90 parts of a linear or radial A-B-A block copolymer and about 10-50 parts of a simple A-B block copolymer, said A-blocks being derived from styrene or styrene homologues and said B-blocks being derived from isoprene; said resin component consisting essentially of about 20-300 parts of tackifier resin for said elastomeric component; all of said parts being parts per one hundred parts by weight of the thermoplastic elastomeric component. 
     
     
       2. A pressure-sensitive adhesive composition according to claim 1, which comprises about 60-80 parts of the A-B-A copolymer and about 20-40 parts of the A-B copolymer, per one hundred parts by weight of the thermoplastic elastomeric component. 
     
     
       3. A pressure-sensitive adhesive composition according to claim 1, which comprises about 50-150 parts of tackifier resin per one hundred parts by weight of the thermoplastic elastomeric component.